Gear-shifting jaw clutch for speed-changing vehicular transmission

Abstract

Two gears idling on a shaft can be selectively coupled therewith by an interposed jaw clutch including a central gear fixed to the shaft and a surrounding ring gear axially slidable thereon for engagement with jaw teeth on either of the two flanking idler gears. Two blocking rings on opposite sides of the central gear are entrained thereby for joint rotation with freedom of limited relative angular displacement by frictional contact with the adjoining idler gears between two extreme relative position in which these rings prevent the shifting of the ring gear into engagement with the jaw teeth of the corresponding idler gear; such engagement is possible only in an intermediate angular position of the respective blocking ring in which several stop teeth on the blocking ring register with matching peripheral indentations on the ring gear. The ring gear has several angularly equispaced inner peripheral recesses accommodating radially slidable keys of which at least one coacts on standstill and at low shaft speeds with respective pairs of bosses on either blocking ring to move the latter into its nonblocking position upon an axial sliding of the ring gear toward it, these keys being centrifugally displaced outwardly at higher shaft speeds so as to be ineffectual.

We claim: 
     
       1. In a transmission including a shaft, a rotary member freely rotatable about the axis of said shaft, said member being provided with a set of jaw teeth, a clutch on said shaft operable to couple said member with said shaft, said clutch having a central body secured to said shaft and an annular tooth carrier nonrotatable on said body but axially shiftable thereon for selective engagement with said jaw teeth, and actuating means for so shifting said tooth carrier, the improvement wherein said clutch is provided with a blocking ring coaxial with said tooth carrier and interposed between the latter and said member, said blocking ring being carried on said body with freedom of limited relative angular displacement by frictional contact with said member between two extreme positions in which said blocking ring prevents engagement of said tooth carrier with said jaw teeth, said blocking ring being frictionally entrainable by said member into a nonblocking intermediate angular position facilitating said engagement upon a passage of said member and said body through a condition of synchronous rotation; said tooth carrier being provided with radially movable weight means mounted for co-operation with coacting formations on said blocking ring, at shaft speeds less than a predetermined limit beyond which said weight means is centrifugally moved out of alignment with said coacting formations, to rotate said blocking ring into said intermediate position.   
     
     
       2. The improvement defined in claim 1 wherein said weight means comprises a plurality of mutually independent keys peripherally equispaced on said tooth carrier. 
     
     
       3. The improvement defined in claim 2 wherein said coacting formations are pairs of bosses separated by axially extending gaps on the periphery of said blocking ring, each of said gaps confronting a respective key and being bounded by camming edges of the associated pair of bosses diverging toward said body for receiving the respective key therebetween upon an axial shifting of said tooth carrier toward said member. 
     
     
       4. The improvement defined in claim 3 wherein said tooth carrier is a ring gear provided with internal jaw teeth mating with complementary teeth on said body, said ring gear being further provided with inner peripheral recesses traversing certain of said internal jaw teeth, said keys being respectively received in said recesses and being provided with angularly spaced axial projections flanking said certain of said internal jaw teeth, said projections lying on a common radius with said bosses at speeds less than said predetermined limit. 
     
     
       5. The improvement defined in claim 4 wherein other of said internal jaw teeth aligned with said bosses are reduced in height to give clearance of said bosses upon an axial shifting of said tooth carrier toward said member. 
     
     
       6. The improvement defined in claim 4 wherein said blocking ring is provided with a plurality of stop teeth received with angular play in peripheral undercuts of said tooth carrier offset from said recesses, said undercuts being bounded by lands having indentations accommodating said stop teeth in said intermediate position. 
     
     
       7. The improvement defined in claim 4 wherein said member and said blocking ring are symmetrically duplicated on opposite sides of said body, said recesses being generally H-shaped with the legs of the H formed by transverse grooves open toward the two symmetrical members and interconnected by a central channel, said projections lying in said grooves and extending on opposite sides of said channel. 
     
     
       8. The improvement defined in claim 7 wherein the two symmetrical blocking rings are provided with common biasing means in the regions of said recesses for urging said blocking rings axially outwardly toward said members. 
     
     
       9. The improvement defined in claim 1 wherein said member is part of a speed-changing gear train between a load coupled to said shaft and an engine coupled to said member, further comprising a hydrodynamic torque converter inserted between said engine and said member. 
     
     
       10. The improvement defined in claim 9, further comprising brake means downstream of said torque converter for arresting said member preparatorily to operation of said actuating means upon substantial standstill of said load.